The present invention relates to a Stirling heating pump.
Stirling heating pumps are known in the art. A known Stirling heating pump has a working piston which is driven by a crank drive and acts upon a compression chamber with which a first heat exchanger, a regenerator formed as the heat accumulator, and a second heat exchanger are connected, whereas an expansion chamber is provided thereabove, and a cam-controlled displacement piston acts upon the expansion chamber. Both pistons displace during the operation practically one gas volume between the compression chamber and the expansion chamber in cyclical controlled manner back and forth. The compression work produced in gas in the compression chamber is taken off in the first heat exchanger as a heat. During displacement of the constantly held gas volume in the cold expansion chamber, the gas flows through the regenerator and gives out the heat remaining in the gas. Thereby the expansion of the gas in the expansion chamber takes place, so that the heat from the surrounding atmosphere can be supplied via the second heat exchanger to the gas. After this, the gas with constant volume is displaced back into the compression chamber. The heat supplied previously into the regenerator is taken off again by the gas. The heat energy given out from such a Stirling heating pump thereby combines the energy recovered from the surrounding atmosphere and the compression energy.
The above described Stirling heating pump operates cyclically in the compression chamber in the pressure region of approximately between 5 and 22 bar. There is a problem to seal the compression chamber from the closed housing for accommodating the crank drive. Generally, the compression chamber is located above the working piston, and the closed crank drive housing is located below the working piston. It is known to provide a diaphragm bellows for sealing a working piston. The diaphragm bellows has the important advantage that it practically has no friction losses and reliably prevents a possible oil fog from flowing from the crank drive housing to the compression chamber in all cases, also in the event of capillary penetration. This is very important inasmuch as the oil fog can after a certain time lead to oil dirtying in the region of the heat exchanger and the regenerator.
Even though these diaphragm bellows provide for the above mentioned advantages, it also causes the problem that the diaphragm bellows performing its intended functions has an insufficient service life. It must be taken into consideration that in the closed crank drive housing a certain pressure, for example an average working pressure of 12.5 bar takes place. Thereby in the working region of 5-22 bar in the compression chamber, the diaphragm bellows is loaded cyclically with a pressure difference of between +10 bar and -7 bar. On the other hand, the replacement of the diaphragm bellows by a normal piston sealing on the working piston is disadvantageous in the sense of a completely reliable sealing of the oil fog from the crank drive housing and in the sense of the friction losses connected therewith.